The present invention relates to a method for improving rheological properties of mineral slurry. More particularly the present invention relates to a method wherein a copolymeric dispersing agent is added to the slurry to disperse silicate minerals. The present invention relates to a flotation method
Flotation is a process where mineral slurry produced from pulverized ore is mixed with foam forming organic chemicals and with the aid of air foam is formed to mineral slurry. Collector chemicals bound the valuable metal concentrate to the surface of the foam bubbles. Mineral concentrate foam is collected from the surface of the flotation cell.
Froth flotation commences by comminution, which is used to increase the surface area of the ore for subsequent processing and break the rocks into the desired mineral and gangue in a process known as liberation, which then has to be separated from the desired mineral. The ore is ground into a fine powder and mixed with water to form a slurry. The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical. The particular chemical depends on which mineral is being refined. This slurry (more properly called the pulp) of hydrophobic mineral-bearing ore and hydrophilic gangue is then introduced to a water bath which is aerated, creating bubbles. The hydrophobic grains of mineral-bearing ore escape the water by attaching to the air bubbles, which rise to the surface, forming a foam or a scum (more properly called a froth). The froth is removed and the concentrated mineral is further refined (Wikipedia).
Serpentinite is a rock composed of one or more serpentine group minerals. Separation of nickel minerals from serpentinite-containing gangue is challenging. Because of lack of good separation from gangue the plants are forced to operate flotation process based on quality of the concentrate with the cost of nickel recovery losses. This significantly decreases the yield and the economy of the operations. Problem with the serpentine is that it contains Mg which is problematic element in nickel smelters. End customers (smelters) have strict limits for Mg and excess Mg decreases the value of the concentrate, in some cases practically to level of non-value product.
Serpentine content can be as high as 30% of incoming flow calculated as MgO. At normal slurry densities the serpentinite forms a non-newtonian viscous jelly that prevents dispersion of air and the passage of air bubbles to the surface of a flotation cell. This problem is generally solved by decreasing the solid content in flotation i.e. increasing water consumption. In worst cases only 10% solid content is used with highly serpentine containing ores. Normal operation is in the range of 30-40% solid content.